India Set to Begin Production of Powerful S5-Class Nuclear Submarines by 2027

India is preparing to take a major leap in its nuclear deterrence capabilities with the upcoming S5-class nuclear-powered ballistic missile submarines (SSBNs), which are expected to enter production by 2027. These submarines will be the largest and most powerful built in India, forming the backbone of the country’s sea-based nuclear arsenal.

Bigger, Stealthier, and More Powerful

The S5-class submarines are projected to have a displacement of around 13,500 tonnes, making them nearly twice the size of the existing Arihant-class SSBNs. They will be powered by a 190 MW pressurized water reactor developed by the Bhabha Atomic Research Centre (BARC), a significant upgrade over the 83 MW reactor used in earlier submarines. This enhanced reactor is designed to run for up to a decade without refueling, giving the submarines greater endurance and stealth.

The submarines are expected to feature pump-jet propulsion technology, which will reduce noise levels and make them harder to detect under water. With an expected endurance of several months at sea, the S5-class will enable India to maintain continuous nuclear deterrent patrols.

Formidable Missile Payload

The defining strength of the S5 will be its missile load. Each submarine is designed to carry 12 to 16 ballistic missiles, including the upcoming K-5 and K-6 submarine-launched ballistic missiles (SLBMs). These missiles are believed to have ranges between 5,000 km and 8,000 km, and the K-6 is expected to carry MIRV (Multiple Independently targetable Reentry Vehicle) warheads, allowing one missile to strike multiple targets.

Future upgrades could see the S5 armed with even longer-range SLBMs under development, further strengthening India’s ability to deter adversaries at greater distances.

Production and Fleet Expansion

A new submarine construction facility has already been developed to support the S5 program, with the capacity to build up to three submarines at the same time. India reportedly plans to build at least four S5-class SSBNs, ensuring that at least one submarine is always on deterrent patrol while others undergo maintenance and training.

Construction of each submarine could take seven to eight years, with the first expected to be completed in the mid-2030s.

Part of India’s Nuclear Triad

The S5-class will significantly strengthen India’s nuclear triad, which relies on land-based missiles, air-delivered weapons, and submarine-launched missiles. SSBNs are considered the most survivable leg of the triad, as they can remain hidden underwater and provide a reliable second-strike capability in the event of a nuclear attack.

With the Arihant-class already in service and the larger S4 and S4 variants* nearing completion, the S5-class represents the next evolutionary step in India’s undersea deterrent.

Strategic Impact

The arrival of the S5-class will bring India closer to the capabilities of global nuclear powers like the United States, Russia, China, France, and the UK, all of which operate advanced SSBN fleets. For India, it ensures a credible, survivable deterrent against both Pakistan and China, reinforcing stability in the Indo-Pacific region.

At a Glance – S5-Class SSBN